1. Field
Aspects of the present invention relate to a polarizing plate, a method for preparing the same, and an optical display apparatus including the same.
2. Description of the Related Art
An organic light emitting diode (OLED) display refers to an emissive display apparatus that emits light through electrical excitation of fluorescent organic compounds. Such a display apparatus has advantages including operability at a lower voltage, reduced thickness, etc. In addition, OLED display apparatuses overcome many of the problems associated with typical liquid crystal display apparatuses involving viewing angle, response times, etc., and have, thus, attracted much attention in recent years.
Generally, an OLED display apparatus includes a glass substrate, an organic electroluminescent section on the glass substrate, and a protective cap having water-absorption properties surrounding the organic electroluminescent section.
Unlike liquid crystal displays, OLED displays do not require a polarizing plate. However, in order to compensate for deterioration in brightness due to reflection of external light by an aluminum plate of an OLED driving panel, an OLED display generally does employ a polarizing plate. The polarizing plate is generally positioned on one surface of the glass substrate.
Typically, a polarizing plate includes a quarter-wavelength (λ/4) retardation film. However, a polarizing plate capable of enabling circular polarization using a single λ/4 retardation film often encounters problems including low lateral reflective visibility and insufficient prevention of reflection of external light.
Japanese Patent Publication No. 2003-090912A discloses a retardation plate that includes a first layer formed of a resin having a positive inherent birefringence value and a second layer formed of a resin having a negative inherent birefringence value.